“This material world is just like smoke, and the spiritual world is just like a blazing fire. The innumerable living entities are prone to fall down to the material world from the spiritual world when influenced by illusory energy, and it is also possible for the living entity to become liberated again when by cultivation of real knowledge he becomes completely freed from the contamination of the material world.” (Krishna, The Supreme Personality of Godhead, Vol 2, Ch 32)